We have identified melanoma antigen gene product MAGE-n as an androgen receptor (AR) coregulator that increases AR activity in the presence of androgen by modulating steroid receptor pi6o coactivator recruitment. Studies outlined in this proposal will determine whether MAGE-n serves as a docking site for AR coregulators in the normal male and female reproductive tract and in polycystic ovarian syndrome (PCOS). Our hypothesis is that MAGE-n modulates AR activity in human ovary and endometrium by facilitating the recruitment of coregulators to the AR transcription complex through direct and indirect mechanisms. Our studies will establish the temporal pattern of MAGE-n expression over the reproductive cycle in the human and monkey ovary and endometrium. We will establish the function of MAGE-n and AR in the endometrium during the window of receptivity to embryo implantation and explore whether temporal changes in MAGE-n influence folliculogenesis and maturation by modulating AR signaling. Our preliminary studies indicate EGF signaling controls MAGE-n coregulator activity. We will determine the effects of EGF on phosphorylation and ubiqutinylation of MAGE-n and how these post-transcriptional modifications alter interactions between AR and coregulators. We will investigate the structural basis for naturally occurring mutations in AR and MAGE-n that alter AR function without changing high affinity androgen binding. A structural relay between the ligand binding pocket and activation function 2 in the ligand binding domain that occurs in response to high affinity androgen binding will be characterized to determine how naturally occurring gene defects can be overcome by selective AR ligands and modulators. Specific aim i will identify the temporal pattern of expression and hormone regulation of MAGE-n relative to AR and other AR coregulators in human and monkey ovary and human endometrium and alterations in expression associated with PCOS. Specific aim 2 will establish the mechanisms whereby MAGE-ii modulates AR transcriptional activity by acting as a coregulator docking site in normal and PCOS ovary and endometrium. Specific aim 3 will determine the mechanisms whereby EGF signaling modulates AR transcriptional activity through phosphorylation and ubiquitinylation of MAGE-ii. Specific aim 4 will establish the functional basis for naturally occurring AR mutations that cause the androgen insensitivity syndrome and determine whether mutations in the MAGE-n gene cause AIS in the male and premature ovarian failure in the female.